[snayko]

Hello, I have a problem with vibration. Happens only when under load (when depress gas pedal). When accelerate from 0-40mph it's noticeable the most. But happens all the time. At freeway speeds I hear howling sound when accelerate.

So need you guys to help me to eliminate wrong versions.
(btw I've replaced flex disk 15k miles ago so I eliminate that for now)

and a couple of remarks: I have a feeling that vibration comes from rear right side but maybe it's just a feeling.
And I've noticed that the car started to stop faster (when I release all pedals) like something in drivetrain is stopping it faster than usual.
And all this started to happen after I did wheel alignment.

So here is my list of causes:
1) center shaft bearing
2) final drive or diff ( I's slightly seeping but level of oil is ok )
3) rear wheel hub bearing (right or left I've checked wheels when car was on jacks it's spinning fine without any noise )
4) rear output shaft (right or left have no visual wear of boots )
5) rear sticky caliper (right or left)

I'm going to inspect it on the lift with a helper who will accelerate so I can hear(by means of stethoscope) some noises or see some vibrations.

But before that want to eliminate wrong versions

[kiel_dafo_kenyg_as]

The flex disk can be toast after only 1000 miles if one doesn't take care about the mounting direction when replacing.
http://blog.bavauto.com/14113/bmw-ho...ex-disc-giubo/

[snayko]

Originally Posted by kiel_dafo_kenyg_as

The flex disk can be toast after only 1000 miles if one doesn't take care about the mounting direction when replacing.
http://blog.bavauto.com/14113/bmw-ho...ex-disc-giubo/

It's installed properly. I know for sure and there are no visual defects on it.
I've checked that first.

[kiel_dafo_kenyg_as]

Then I'd suspect the center shaft bearing. Never had it loose on a E9x so I can't be of great help.

[snayko]

Ok thanks.
Will see what stethoscope is saying.

[Efthreeoh]

I just found this thread. I've posted this elsewhere. My car had the same problem. I finally figured out it was the dual-mass flywheel. Not sure if your car is an automatic or manual. Only the manual transmission cars have a dual-mass flywheel.

[Volasko]

When you replaced the flex disk did you remove the center shaft bearing bracket? You could have installed it upside down. It is possible to do this and have it bolt up completely normally. I did this when I rebuilt my rear end and had a strange vibration only when accelerating. The drive shaft universal was working overtime due to the fact it wasn't completely straight. When under load the vibration would rear its ugly head, when maintaining speed it was not noticeable. Worth a look if you already have been working down in that area.

[snayko]

Originally Posted by Volasko

When you replaced the flex disk did you remove the center shaft bearing bracket? You could have installed it upside down. It is possible to do this and have it bolt up completely normally. I did this when I rebuilt my rear end and had a strange vibration only when accelerating. The drive shaft universal was working overtime due to the fact it wasn't completely straight. When under load the vibration would rear its ugly head, when maintaining speed it was not noticeable. Worth a look if you already have been working down in that area.

When I replaced my flex disk I did not remove the center shaft bearing bracket.
But I already fixed the problem by replacing center shaft mount(bearing).

It's possible to install it upside down but in this case it would look strange with empty space on top and driveshaft would not be straight. So I hesitated not for a long time